Introduction

Anemia is functionally defined as an insufficient RBC mass to adequately deliver oxygen to the peripheral tissues. 

It may be characterized by decreased RBC mass, decreased hemoglobin concentration, or decreased hematocrit for the appropriate age, sex and altitude of residence.

It may be due to increased RBC clearance, decreased RBC production, or both (intrinsic or extrinsic pathways).

According to WHO, hemoglobin <13 g/dl in males, <12 g/dl in non-pregnant females, and <11 g/dl in pregnant females is considered as evidence of anemia.

Etiology

Decreased hemoglobin synthesis:

• Lack of nutrients: iron, vitamin B12, folic acid

• Bone marrow failure: due to drugs, chemotherapy, infections etc.

Increased hemoglobin loss:

• Hemorrhage - RBC loss

• Hemolysis - RBC destruction 

Decreased RBC production:

• Disturbance in stem cell proliferation, or differentiation due to bone marrow infiltration by cancer cells, infection, etc.

Life cycle of RBC

Classification of anemia

Reticulocyte Production Index

It gives the functioning of the bone marrow.

Symptoms of Anemia

• Fatigue or low-energy

• Increased heart rate

• Shortness of breath 

• Headache/dizziness 

Iron Deficiency Anemia

Normal iron content in the body is 50 mg/kg in males and 40 mg/kg in females.

Distribution of iron:

• 67% in hemoglobin 

• 27% in ferritin 

• 3.5% in myoglobin

• 0.08% in transferring

Forms of iron in the body:

The iron is absorbed in Ferrous form (Fe2+)

The circulatory and storage form of iron is Ferric (Fe3+)

It is primarily stored as ferritin in bone marrow, macrophages, duodenum, liver and brain.

Stages of iron deficiency anemia 

Prelatent:

Reduction in iron stores without reduction in serum iron levels.

Features - normal hemoglobin, normal MCV, normal transferrin saturation, increased iron absorption, decreased serum ferritin, decreased marrow iron.

Latent: 

Iron stores are exhausted but the serum iron level is normal.

Features - normal hemoglobin, normal MCV, increased total iron binding capacity, decreased serum ferritin, decreased transferrin saturation, marrow iron absent.

Iron deficiency anemia:

Blood hemoglobin concentration is below the lower limit of normal.

Features - decreased hemoglobin, decreased MCV, increased total iron binding capacity, decreased serum ferritin, decreased transferrin saturation, marrow iron absent 

Causes 

Increased iron demand:

• Infancy 

• Adolescence 

• Pregnancy 

• Erythropoietin therapy ( in CKD)

Increased iron loss:

• Chronic blood loss

• Menses

• Acute blood loss like road traffic accidents, hemorrhoids etc

• Phlebotomy as treatment of polycythemia vera 

• Blood donation 

Decreased iron intake/ absorption:

• Inadequate diet 

• Malabsorption from disease (coeliac sprues, Crohn's disease)

• Malabsorption from surgery (gastrectomy, other bariatric surgery)

• Acute or chronic inflammation 

Clinical features 

• Geographic tongue - bald tongue due to loss of filiform papilla from the periphery to the centre

• Flattening/ koilonychia of nails

• Angular stomatitis

• Dysphagia/ esophageal webs (Plummer-Vinson Syndrome)

• Achlorhydria/ gastritis

• Pica - craving for materials with no nutritional value (clay, ice, etc.)

Plummer Vinson Syndrome: A triad of iron deficiency anemia, post cricoid/ esophageal webs, dysphagia.

Lab findings in iron deficiency anemia 

• Decreased MCV 

• Decreased RDW

• Microcytic hypochromic

• Pencil cells, target cells

• Anisocytosis

• Decreased RBC count

• Decreased serum iron

• Increased total iron binding capacity 

• Decreased transferrin saturation 

• Decreased ferritin (most sensitive)

• Marrow iron absent

Treatment 

Oral iron supplements: 

It is given for iron deficiency erythropoiesis, pre-latent stages with negative iron balance. It should be continued for 6 to 12 months post-correction.

Parenteral iron therapy:

It is preferred nowadays.